Lubricant feed system for use in the journal of a crankshaft

Abstract

There is disclosed a lubricant feed system for use in a journal of a crankshaft comprising first bearing supporting portions formed in a cylinder block, each having a peripheral surface, second bearing supporting portions formed in caps, each having a peripheral surface, first bearings in the form of half shells arranged on the peripheral surfaces of the first bearing supporting portions, second bearings in the form of half shells arranged on the peripheral surfaces of the second bearing supporting portions and an oil main gallery. In this arrangement, annular grooves are formed on the peripheral surfaces of the first and second bearing supporting portions and oil grooves are circumferentially formed at the inner peripheral surfaces of the first bearings. Apertures are formed at the first bearings to communicate the annular grooves with the oil grooves. The inner peripheral surfaces of the second bearings are made flat. Further, a bridge is mounted on the undersides of the bearing caps and the oil main gallery is provided in the bridge. The oil main gallery is communicated with the annular grooves in the second bearing supporting portions. Oil in the oil main gallery is fed to the annular grooves to directly cool the second bearings to which explosive loads are applied.

What is claimed is: 
     
       1. A lubricant feed system for a journal of a crankshaft comprising first bearing supporting portions formed in a cylinder block, each having a peripheral surface, second bearing supporting portions formed in caps, each having a peripheral surface, first bearings arranged on said first bearing supporting portions, second bearings arranged on said second bearing supporting portions, and at least one oil main gallery, wherein annular grooves are circumferentially formed at the respective first and second bearing supporting portions, wherein oil grooves are circumferentially formed at the inner peripherial surfaces of said first bearings and apertures are formed at said first bearings to communicate said annular grooves with said oil grooves, wherein the inner peripheral surfaces of said second bearings are made flat, and wherein said oil main gallery is communicated with said annular grooves at said second bearings respectively. 
     
     
       2. A lubricant feed system according to claim 1, wherein said oil main gallery is provided in said bearing caps. 
     
     
       3. A lubricant feed system according to claim 1, wherein a bridge is fixedly mounted on the undersides of the caps and said oil main gallery is provided in said bridge.